Ignition timer



Dec. 29, 1942. M, MALLORY IGNITION TIMER Original Filed Jan. 4, 1937 '.3Sheets-Sheet 1 1M. MALLRY IGNITION TIMER f Original Filed Jan. 4, 1937 3Sheets-Sheet 2 Dgc. 29, 1942. M. MALLORY IGNITION TIMER Original 'FiledJan. 4, 1937 3 Sheets-Sheet 3 Patented Dec. 29, 1942 UNITED STATESPATENT OFFICE 2,306,889 v IGNITION TIMER Marion Mallory, Detroit, Mich.

Original application January 4, 1937, Serial No. 119,006. Divided andthis application October 4, 1940, Serial No. 359,771

Claims. .(Cl. 200-31) This invention relates to ignition timers for internal combustion engines and more especially to the automatic controlthereof in accordance with the speed and load. This application is adivision of application Serial No. 119,006, filed January n 4, 1937,abandoned March l, 1941.

For smooth idling, an extreme retardation of the timing is necessary,but upon a slight opening of the throttle, there should be anappreciable immediate advance of the timing. Following this, thereshould be a further gradual advance as the speed increases, but when theengine is working under full load with wide open throttle at either lowor high speeds, it is desirable to retard the advance to some extent toprevent detonation.

It has heretofore been proposed to use centrifugal means to'advance thespark in proportion to the speed, and supplemental spark advancing meanscontrolled by the suction of the engine intake. In the operation ofdevices of this kind as heretofore proposed however, either the suctionis not immediately effective to advance the spark as soon as thethrottle starts to open, or it is not rendered ineffective when thethrottle is wide open.

With the above facts in mind, it is an object of the present inventionto provide, in addition to a centrifugal spark advance, a supplementalsuction controlled spark advancing means and means in the nature of asuction controlled valve to render the suction controlled sparkadvancing means eective at the proper time. This supplemental sparkadvancing means is connected into the intake manifold but is out oitherefrom at the proper time by the valve, which is connected to theintake on the atmospheric side of the throttle valve when the latter isclosed for idling. As soon as the throttle starts to open, the suctioncontrolled valve is subjected to suction from the inflowing fuel and,since it is normally held closed by a light spring, it will immediatelyopen, thus subjecting the spark control to the action of the high vacuumof the manifold, which advances the spark. With the throttle wide openat either high or low speeds, the suction may be high enough to operatethe suction controlled spark advance. However, the suction in the intakepassageway will be insuflicient to open the valve to permit the vacuumspark control to advance the spark.

It is also an object of the invention to provide convenient means toeasily adjust the maximum range of speed governor advance, the rate ofsuch advance, andthe maximum range of suction controlled advance, sothat these characteristics of the spark timing may be properly set forthe individual timer or the individual engine with which the timer isused.

The above and other objects and advantages of the invention will be moreparticularly explained in connection with the accompanying drawings, inwhich Fig. 1 is a horizontal section through the timer housing above thebrake plate, showing the suction controlled valve in a position to cutofi the vacuum between the brake and the manifold, allowing the brake toengage and hold the timer in a retard position.

Fig. 2 is a sectional view showing the suction control valve of Fig. 1in a position to connect the brake with the intake manifold vacuum foradvancing the spark.

Fig. 3 is a vertical section through the timer housing, the circuitbreakers and springs being omitted.

Fig. 4 is a plan view of the circuit breakers and plate.

Fig. 5 is a section taken on the line 5-5 of Fig. 3.

Fig. 6 is a section taken on the line E-G of Fig. 3.

Figs. 7 and 8 are charts representing the governor curves resulting fromVarious adjustments of the timer.

As illustrated in Figs. 1, 2 and 3, the invention is associated with anengine intake manifold l0 having a fuel intake passageway I l with athrottle valve I2 therein. The housing 23 is formed with a shank 33which is lined with a bushing 34 to provide a bearing for the timershaft 35 adapted to be driven from the engine. The shaft 35 has areduced extension 36 on which is mounted a sleeve 31 carrying thecircuit breaker cam 38. A circuit breaker plate 39 ts into the housing23 and is secured by insulated screws 40 and 4|, to which the circuitbreaker springs 42 and 43 are also secured. The terminal screws 40 and4I are electrically connected by an insulated conductor 44 and the innerends of the springs 42 and 43, which constitute parts of the primarycircuit, are secured to overlapping circuits breakers 45 and 45. Sincethe mountings of the latter do not constitute a part of the presentinvention, it is not necessary to describe the same here in detail.

The sleeve 3l is formed with a flange 5G to which a governor plate 55 isclamped by means of a clamping member 51 and screws 53. A drive plate t9is iiXed to the shaft 35. A circular brake plate 26 floats on the timershaft 35 between the plates 49 and 55.

The plate 55 and circuit breaker cam 38 are adapted to be advanced withreference to the brake plate 26 by centrifugal governor mechanism, whichmay be termed the primary timing control and which will be hereinaftermore particularly described.

The brake plate 26 is adapted to be held in an advanced position withreference to the drive plate 49 by a spring 52, except when it is heldin retard position by the engagement of a brake 25 with its periphery.'I'his brake is carried by a piston 24 which operates in a cylinder 22connected to the timer housing 23. A spring 21 holds the brake inengagement with the plate 426 until there is suflicient vacuum developedin the cylinder to overcome the action ofthe spring, thereby retractingthe piston and permitting an immediate advance of the plate 26 with acorresponding advance of the timing. This may be termed the supplementalor vacuum timing control.

The vacuum is developed in the cylinder 22 through a conduit I3 which isconnected through a valve casing I4 and conduit I5 to the manifold I8.Communication between the conduits I3 and I5 is adapted to be cut off bya valve I6, which is normally held closed by a spring I1. The end of thecasing beneath the valve has a passageway I8 leading into the intake IIimmediately above the throttle valve I2 when the latter is in closed oridling position. A vent I9 in the other end of the casing I4 permits thevalve to be opened by suction through the passageway I8 in opposition tothe spring I1. An annular groove 2,8 in the valve I6 is at all times incommunication with the conduit I3, Another annular groove 2l Ybleedsinto the passageway I8. Thus the valve is prevented from becomingvacuum-locked against the casing wall.

The centrifugal governor mechanism comprises two governor weights 41 and48. One of these weights,' as 48, is pivotally mounted on a pin 53secured to the plate 26. The other weight 41 is pivotally mounted on apin 54 which projects downwardly from the plate 55 secured to the sleeve31. As the weights fly outwardly about their pivots 5d and 53 under theinfluence of centrifugal force, the edges 59 roll on each other, forcingthe pivots 54 and 53 farther apart and causing an advance of the plate55, sleeve 31 and circuit breaker cam 38 with reference to the plate 25.The extreme outward movement of the Weights 41 and 48 is limited bytheir engagement with the pins 68 and 6I secured in the respectiveplates 55 and 26.

The characteristics of the spark advance curve necessary for the mosteconomical operation vary widely in different cars and differentengines, and even in the same engine at different periods of its life.This invention therefore p-rovides for universal adjustment of thesecharacteristics.

In order to adjustably limit the maximum advance of the governor plate55 and cam 38 with reference to the plate 26, as controlled by thegovernor weights 41 and 48, an arm 68 is mounted for pivotal adjustmentabout the shaft 36 and is secured in its adjusted position by a clampingscrew 65, which extends through a slot 10 in said arm into the plate 26.The cam edge 1I of the arm 68 is adapted to engage the downwardlyprojecting end of the pin 54, which extends into a slot 12in the plate26, and thereby progressively decreases the maximum range of advance ofthe plate 55 with reference to the plate 26, as the arm is adjustedtowardthe left. The

position of the adjustment is indicated fon the 76 scale 13 by thepointer 14 on the end of the arm 68,

The action of the governor weights 41 and 48 in advancing the plate 55is resisted by a spring 15, which is so mounted that the point where theadvance begins and the ratio of such advance to the increase in speedmay be adjusted. One end of the spring 15 is connected to a pin 16secured to an arm 11 which is mounted for adjustment about a pivot pin18secured to the under side of the plate. The pin 16 projects upwardlythrough an arcuate slot 1S in the plate and the .arm 11 is secured inadjusted position by a clamping screw which extends through a slot 8|into the arm. The other end of the spring 15 is connected to a pin S2 onan arm 83 which is pivotally mounted on the pin 18. An arm S4 is mountedfor pivotal adjustment about a pin on the plate 55 and is secured inadjusted position by a clamping Screw 86, which extends through a slot81 in said arm and into the plate 55. A pin 88 secured to the arm 84engages an arcuate slot 89 in the arm 83.

Adjustment of the arm B4 about its pivot 85 Varies the position of thepin 88 in the slot 89 and the consequent leverage of the arm 83 aboutits pivot 18', when` the governor weights act to advance the plate 55 inopposition to the resistance of the governor spring 15 transmittedthrough the pin 82, arm 83, pin 88 and arm 84 to the plate 55. Thisadjustment therefore varies the tension of the governor spring and theratio of the speed controlled advance of the timing as compared to thespeed.

Adjustment of the arm 11 about its pivot 18 toward the outer edge of theplate 26 increases the tension on the governor spring 15.

Adjustment of the arm 68 about the shaft 36 as va center causes said armto cover more or less of the end of the slot 12, into which the pinj54projects, and the engagement of the pin with the edg'e1l `of the armvariably limits'the vmaximum advance ofthe plate 55 and consequently themaximum speed controlled advance of the spark.

The brake plate 26 is held adjacent the drive plate 49 by two pins 5,8and 5i!a which are inserted through slots 5I and 5Ia in the brake plateand secured in the drive plate. These slots therefore limit therotational displacement ofthe plate 26 with reference to the 'plate 49.In order to adjustably limit the maximum relative advance of the plate26, and consequently the vacuum controlled spark advance, an arm 62 ismounted for adjustment about a pivot 63 on the plate 26 and is securedin adjusted position by a clamping screw 64 which extends through a slot65 into said plate. The inclined-end 66 of the arm 62 is adapted` toengage the head of the pin 58 and thereby progressively limit theeffective length of the slot 5I. The maximum advance-of the bra-keAplate. 2,6,- thus limited, is indicated by the point Yof the arm 62 ronthe scale 61.

In theoperation of the vacuum controlled advance, the valve I6 is.closed whenever the throttle valve isV closed. In the structureillustratedY in Fig. 1, there willbe under such conditions no vacuum inthe cylinder 22, the brake 25 will en-v gage the brake .plate-,26, thelatter will be held -in retarded position, and there will be anextremecomparatively high vacuum in the manifold l0, which willimmediately cause a maximum vacuum advance of the spark. This advancemay be in the neighborhood of or 15, depending upon the adjustment ofthe arm 62. This vacuum advance is added to the speed controlled sparkadvance which increases gradually through a predetermined range of speedand which is effected by advancing the circuit breaker cam with respectto the brake plate 26.

The strength of the spring I1 is so chosen that it overcomes the vacuuminduced by the flow through the open intake passageway at a speed in theneighborhood, say, of 50 miles per hour. This renders the vacuum sparkadvancing means ineffective, so that the spark advance is then entirelydependent upon the centrifugal governor. This moderate recession fromthe maximum spark advance is desirable at the highest speeds to preventdetonaton.

Adjustment of the arm 62 about its pivot 63 causes the end 66 of the armto variably limit the range of movement of the brake plate 25 withreference to the plate 49, thereby adjustably limiting the possibleadvance of the spark when the piston 24 is retracted by the vacuum inthe manifold.

From the foregoing description, it will be seen that I have providedmeans to advance the timing in accordance with speed throughout apredetermined adjustable range and, in addition thereto, improved vacuumcontrolled means to cause a predetermined sparkadvance upon a changefrom idling to low speed travel, this vacuum controlled means beingineffective for advancing the spark at the highest speeds, or when theengine is working under la heavy load with open throttle.

The timer also has all the adjustments necessary to secure the desiredspark advance curve for the most satisfactory performance of any givenengine, as illustrated in Figs. 7 and 8. As above stated, the desiredrate of spark advance by the governor, as compared to increased speed ofthe engine, is obtained by variation in the tension of the governorspring 75, which is effected by adjusting the arm 84. Each graduation onthe edge of the slot 89 represents a difference of approximately 400 R.P. M. on the governor advance curve. These curves for differentadjustments are represented at A, B, C, D, E, F, in Fig.

7. When adjusting the governor for a smaller advance, such as or less,to finish at 4000 R. P. M. or later as illustrated by governor advancecurves G, H, I, J, K, L, it may be necessary to place additional tensionon the governor spring 'i5 by adjusting the arm 'l1 toward the outeredge of the plate, as above explained. Curves A, B and C may be producedby using an 8-ounce governor spring. Curves D to L inclusive may beproduced by using a 16ounce governor spring.

When the engine is operating under full throttle and heavy load and thevacuum in the intake manifold drops to approximately 12 mercury orunder, the spring 21 will cause the brake 25 to engage the plate 26,bringing it into retard position and effecting a like retardation of thecentrifugal governor assembly and circuit breaker cam. The governorcurve Will then be similar to that shown at A. As the engine speedincreases, or the throttle is partly closed, the vaeuum in the intakemanifold will build up to a point in excess of 12" mercury, at whichpoint the piston 24 Will be retracted, releasing the brake plate 26,whereupon the governor drive spring 52 will immediately advance thebrake plate and the governor and cam assemblies. The governor will thenproduce a light load curve similar to that shown by the broken line A',which has for illustration been set 10 higher than the load curve A.

On some engines the initial timing is set very close to top dead center.With this setting a rapid intermediate advance of the governor isnecessary from approximately 400 R. P. M. to 800 R. P. M. of the engine,as shown by curves P, Q, R, S, on Fig. 8. To produce these curves, it isnecessary to use a special governor spring lever adjustment arm 84,stamped 6, 10, 12o or 14, indicating the point at which the sloweradvance of the timing begins. With this adjustment arm, a 2li-ouncegovernor spring should be used. The normal position of the spring postI6 is in the end of the slot 19 nearest the center of the plat-e. Incase the governor advances too fast through the lower speed range,resulting in a slight spark knock, the spring post 'I6 should beadjusted toward the other end of the slot.

While the suction control of the spark advance is shown in connectionwith a brake adapted to be applied to a plate that carries the timingmechanism, it will be apparent that the same suction control may be usedwith any other type of timing mechanism, whether the spark is advancedby moving the housing, the circuit breaker plate, circuit breaker cam,or the complete governor assembly. Various other details may also bemodified without departing from the scope of the invention as defined inthe appended claims.

I claim:

1. An ignition timer for an internal combustion engine comprising arotatable timer shaft, a circuit breaker cam mounted on and driven bysaid shaft, said cam adapted to have a limited relative rotativemovement on said shaft, centrifugal means for advancing the cam on saidtimer shaft, and a plate also mounted on said shaft and adapted to havea limited relative rotative movement thereon, said cam and plate alsoadapted to have a limited relative rotative movement on said shaft withrespect to each other, and means connecting said plate and cam wherebyadvancing said plate on said shaft effects a corresponding advance ofsaid cam on said shaft, said centrifugal means advancing said cam onsaid shaft independently of said plate.

2. An ignition timer for an internal combustion engine comprising arotatable timer shaft, a circuit breaker cam mounted on and driven bysaid shaft, said cam adapted to have a limited relative rotativemovement on said shaft, centrifugal means for advancing the cam on saidtimer shaft, and a plate also mounted on said shaft and adapted to havea limited relative rotative movement thereon, said cam and plate alsoadapted to have a limited relative rotative movement on said shaft withrespect to each other, and means connecting said plate and cam wherebyadvancing said plate on said shaft effects a corresponding advance ofsaid cam on said shaft, said centrifugal means advancing said cam onsaid shaft independently of said plate and independently of saidbelow-mentioned suction controlled means, and suction controlled meansfor advancing said plate on said shaft.

3. An ignition timer for an internal combustion engine comprising arotatable driving member, a circuit breaker member mounted on and drivenby said driving member and having a limited rotative movement relativeto said driving member, a plate also mounted on said driving member andhaving a limited rotative movementv relative to said driving member,said circuit breaker member also having a limited rotative movementrelative to said plate, centrifugal means for advancing the circuitbreaker member on said shaft and with respect to said plate andindependently of said below-mentioned suction controlled means, andsuction controlled means for advancing both the said plate and thecircuit breaker member as a unit on said driving member.

4. An ignition timer for an internal combustion engine comprising arotatable timer shaft, a circuit breaker cam mounted on and driven bysaid timer shaft and having a limited rotative movement relative to saidtimer shaft, a plate also mounted on said timer shaft and having alimited rotative movement relative to said timer shaft, said circuitbreaker cam also having a limited rotative movement relative to saidplate, centrifugal means for advancing the circuit breaker cam on saidshaft and with respect to said plate and independently of saidbelow-mentioned suction controlled means, and suction controlled meansfor advancing both the said plate and the circuit breaker cam as a uniton said timer shaft.

v5. An ignition timer for an'internal combles.- tion engine comprising atimer shaft, a plate rigidly connected thereto, a second plate having anignitioncam mounted thereon, the second plate being free to oscillate alimited distance on said timer shaft, a spring connected between thei-lrst and second named plates which tends to hold'the second namedplate to its limited movement in the direction of rotation of timershaft, a friction brake to engage the se-cond named plate and overcomesaid spring to hold the second named plate and said ignition cam to itslimited movement in a direction opposite to that of said timer shaft, agovernor Weight pivetedly mounted on second named plate, a third plateand a cam mounted on said plate, both cam and said third plate beingfree to oscillate on said timer shaft, a second governor Weightpivotedly mounted on the third named plate, said second governor weightengaging with the first governor weight to advance the third named plateand cam as the speed of the said timer shaft in creases, and springmeansV connecting the second and third named plates together to resistthe power of the centrifugal governor Weights.

MARION MALLORY.

